Photobromination of cinnamic acid

Quantum Yields, < , for Photobromination of Cinnamic Acid Temperature 30.6° Wave length 4,358A... 

According to another hypothesis frequently suggested, the bromine atoms combine with bromine molecules to give triatomic bromine molecules which are rather unstable and after reaction they regenerate the bromine atoms, ready to repeat the cycle. This chain was applied to the photobromination of cinnamic acid by Purka-yastha and Ghosh.41... 

The behavior of a photochemical chain reaction can sometimes be described rather simply in terms of the number of photons absorbed and the chain length. In the photobromination of cinnamic acid it is seen from Fig. 32 that the quantum yield is nearly proportional to the concentration of bromine cB in moles per liter. Then as an approximation... 

Example Photobromination of cinnamic acid to dibromocinnamic acid was carried out in blue light of wavelength 440 nm at 310 K using light intensity of 1.5 10 3 J per second. An exposure of 20 minutes produced a decrease of 0.075 millimole of bromine. The solution absorbed 80 per cent of the light passing through it. Calculate the quantum yield of the reaction. 

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